Conventional fluororesin coating compositions are dispersions obtained by dispersing fluororesin particles having an average particle diameter of 1 .mu.m or less into a liquid medium such as water with the aid of a surfactant (as described, for example, in JP-A-60-252381), and coating films having few defects have rarely been obtained therefrom because of the low interparticle cohesive force of the fluororesin particles. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".) In particular, if the coating compositions are applied thickly so as to form coating films with thicknesses exceeding 20 to 30 .mu.m by a single coating operation, the result has often been that cracks are developed in the thus-formed coating films or the coating composition applied on substrates suffer cissing on the substrate surfaces to cause depression defects.
It has, therefore, been necessary that the coating operation be repeatedly conducted in order to obtain a large-thickness coating film.
In contrast, powdered fluororesins for use in electrostatic coating, which have average particle diameters as large as 5 .mu.m or more (as described, for example, in JP-B-62-10429), have been able to form defect-free coating films as thick as 50 to 80 .mu.m even through a single coating operation because their interparticle cohesive force is high particularly where the particles are spherical. (The term "JP-B" as used herein means an "examined Japanese patent publication".)
However, electrostatic coating with fluororesin powders has been defective in that control of film thickness is difficult and coating films uniform in thickness are difficult to obtain.
As described above, it has been difficult for the conventional fluororesin coating compositions to give coating films having few defects and, further, it has been difficult for the powdered fluororesins for use in electrostatic coating to give coating films having uniform thicknesses.